The present invention generally relates to a tray tier stacking apparatus for sequentially stacking trays one by one, which trays are adapted to align, store and feed components.
Conventionally, components were stored, aligned, and fed by the use of a vibration feeder or the like during a feeding operation of the components in an assembly line and so on. When the precision components such as semiconductors, which are likely to be affected by vibrations and shocks, are handled or a plurality of components engaged previously are to be provided with compound components, the alignment and the feeding thereof cannot be effected because in the vibration feeder the compound components are mutually entangled because of the complicated shapes thereof. Thus, the vibration feeder cannot be used. In order to solve the problem, a feeding system is employed in which the components are fed to an assembly station while accommodated in a tray. After being loaded, the tray with each component is moved under a numerical value control to a feeding station. The tray has an indentation for establishing an aligned position of the tray at the feeding station. The orientation of the components is set by the placement thereof on the inner side bottom face of the square tray-shaped containers (trays) composed of soft material such as vesicatory sterol or the like. As many trays are required to facilitate mass production, the trays with components loaded therein and the trays after the components have been fed therefrom are often stacked. A conventional tier stacking apparatus for stacking such trays has the structure shown in FIG. 4. Also, the tray tier stacking operation is shown in FIG. 5. Namely, as shown in FIG. 5(a), a pawl 101 supports a tier 14 of trays already stacked and a new tray 15 in a raised condition is fed below the tier 14 by moving, placing apparatus 21. As shown in FIG. 5 (b), the pawl 101 is lowered to place the tray tier 14 on the tray 15. Furthermore, as shown in FIG. 5 (c), the pawl 101 lowers. The tip end 101a of the pawl 101 is inserted into a stepped portion 20, rubbing against the side face of the tray 15. Then, the pawl 101 adds the tray 15 to the tray tier 14 and is raised. The trays are adapted to be sequentially stacked one by one by the repetition of this operation.
However, in such an apparatus as described hereinabove, the pawl rubs against the side face of the tray when it is lowered and produces powder from the grinding of the tray. Thus, there is a problem in that this apparatus cannot be used in a clean environment in which powder should not be produced. Also, although it has been attempted to solve the above-described problem by the use of a plurality of driving apparatuses which move the pawl in both vertical and lateral directions so as to prevent such rubbing of the trays as described hereinabove, the cost of such apparatuses is high and the space required to accommodate such apparatuses is large.